Electronic devices having a layer overlying an edge of a different layer and a process for forming the same

ABSTRACT

An electronic device includes a radiation-emitting component, a radiation-responsive component, or a combination thereof. In one embodiment, the electronic device includes a substrate and a first structure overlying the substrate. The electronic device also includes a second structure that includes a first layer, wherein the first layer has a first refractive index, and the first layer includes a first edge. The electronic device further includes a second layer overlying at least portions of the first structure and the second structure at the first edge. The second layer has a second refractive index that is lower than the first refractive index. In another embodiment, the first structure includes a layer having a perimeter and a pattern lying within the perimeter. The pattern extends at least partly though the first layer to define an opening with a first edge. In another embodiment, a process is used to form the electronic device.

FIELD OF THE INVENTION

The invention relates generally to electronic devices and processes, andmore specifically to electronic devices having layers overlying edges ofother layers and processes for forming those devices.

BACKGROUND INFORMATION

Many electronic devices are designed to emit or respond to radiation.Examples of electronic devices include Organic Light Emitting Diodes(OLEDs). OLEDs are promising for display applications due to their highpower conversion efficiency and low processing costs. OLEDs includeorganic active layers that can emit or respond to the radiation.

A waveguide (also called a “light pipe”) may be formed within anelectronic device at an interface between layers having dissimilarrefractive indices. The waveguide effect can occur when radiationpropagating within a layer having a higher refractive index is reflectedat an interface with another layer having a lower refractive index. Thewaveguide effect can cause radiation to propagate laterally as opposedto propagating towards the user of the electronic device. In electronicdevices, the lateral propagation of radiation can reduce the efficiencyof the electronic device (require more power for a desired level ofintensity), increase optical cross talk between pixels, or a combinationthereof. Conventional wisdom within the art is to reduce or eliminatethe waveguide effect as much as possible.

SUMMARY OF THE INVENTION

An electronic device includes a radiation-emitting component, aradiation-responsive component, or a combination thereof. In a firstaspect, the electronic device includes a substrate and a first structureoverlying the substrate, wherein the first structure is an electricallyactive structure. The electronic device also includes a second structureoverlying at least portions of the first structure and the substrate.The second structure includes a first layer, the first layer has a firstrefractive index, and the first layer includes a first edge. Theelectronic device further includes a second layer overlying at leastportions of the first structure and the second structure. The secondlayer has a second refractive index that is lower than the firstrefractive index, and the second layer includes a first portion and asecond portion. The first portion of the second layer overlies both thefirst structure at the first edge and the second structure, and thesecond portion of the second layer overlies the first structure but notthe second structure.

In a second aspect, an electronic device includes a substrate, and afirst structure overlying the substrate. The first structure includes afirst layer having a perimeter and a pattern lying within the perimeter,and the pattern extends at least partly though the first layer to definean opening with a first edge. The electronic device also includes asecond structure overlying the opening and at least portions of thefirst structure and the substrate. The second structure includes asecond layer that includes a second edge. The electronic device stillfurther includes a third layer overlying at least portions of the firststructure and the second structure. The third layer includes a firstportion and a second portion, the first portion of the third layeroverlies the first structure and the second structure at the secondedge, and the second portion of the third layer overlies the firststructure but not the second structure.

In a third aspect, a process for forming an electronic device includesforming a first structure over a substrate, wherein the first structureis an electrically active structure. The process also includes forming asecond structure over at least portions of the first structure and thesubstrate. The second structure includes a first layer, the first layerhas a first refractive index, and the first layer includes a first edge.The process further includes forming a second layer overlying the firststructure and the second structure. The second layer has a secondrefractive index that is lower than the first refractive index, thesecond layer includes a first portion and a second portion, the firstportion of the second layer overlies the first structure at the firstedge of the first layer and overlies the second structure, and thesecond portion of the second layer overlies the first structure but notthe second structure.

The foregoing general description and the following detailed descriptionare exemplary and explanatory only and are not restrictive of theinvention, as defined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated by way of example and not limitation in theaccompanying figures.

FIG. 1 includes an illustration showing how radiation from an emissionsite may propagate through different layers within an electronic device.

FIGS. 2 and 3 include illustrations of a plan view and a cross-sectionalview, respectively, of a portion of an array within an electronic deviceafter forming first electrodes.

FIGS. 4 and 5 include illustrations of a plan view and a cross-sectionalview, respectively, of the array of FIGS. 2 and 3 after forming wellstructures.

FIG. 6 includes an illustration of a cross-sectional view of an enlargedportion of FIG. 5 near an edge of a well structure.

FIGS. 7-9 include illustrations of cross-sectional views of alternativeembodiments for the shape of the edge of the well structure.

FIG. 10 includes an illustration of a cross-sectional view of the arrayin FIG. 5 after forming an organic layer including a hole-transportlayer and an organic active layer.

FIGS. 11 and 12 include illustrations of a plan view and across-sectional view, respectively, of the array of FIG. 10 afterforming second electrodes.

FIG. 13 includes an illustration of a plan view of the array in FIGS. 11and 12 during operation, wherein halos appear near edges of theradiation-emitting components.

FIG. 14 includes a plot of intensity as a function of distance, whereinemission intensity within the halo is larger than emission intensitynear the center of the radiation-emission component.

FIGS. 15 and 16 include illustrations of a plan view and across-sectional view, respectively, of a portion of an array within anelectronic device after forming slotted first electrodes.

FIG. 17 includes an illustration of a cross-sectional view of anenlarged portion of FIG. 16 after forming well structures near the edgeof a first electrode and within a slot.

FIGS. 18 and 19 include illustrations of a plan view and across-sectional view, respectively, of a portion of an array within anelectronic device after forming first electrodes having a checkerboardpattern.

FIG. 20 includes an illustration of a plan view of radiation-emittingcomponents having different shapes and corresponding halos for thoseradiation-emitting components.

Skilled artisans appreciate that elements in the figures are illustratedfor simplicity and clarity and have not necessarily been drawn to scale.For example, the dimensions of some of the elements in the figures maybe exaggerated relative to other elements to help to improveunderstanding of embodiments of the invention.

DETAILED DESCRIPTION

An electronic device includes a radiation-emitting component, aradiation-responsive component, or a combination thereof. In a firstaspect, the electronic device includes a substrate and a first structureoverlying the substrate, wherein the first structure is an electricallyactive structure. The electronic device also includes a second structureoverlying at least portions of the first structure and the substrate.The second structure includes a first layer, the first layer has a firstrefractive index, and the first layer includes a first edge. Theelectronic device further includes a second layer overlying at leastportions of the first structure and the second structure. The secondlayer has a second refractive index that is lower than the firstrefractive index, and the second layer includes a first portion and asecond portion. The first portion of the second layer overlies both thefirst structure at the first edge and the second structure, and thesecond portion of the second layer overlies the first structure but notthe second structure.

In one embodiment of the first aspect, the second structure includes awell structure. In another embodiment, the first structure furtherincludes a third layer having a third refractive index. A firstdifference is an absolute value of the first refractive index minus thesecond refractive index, a second difference is an absolute value of thefirst refractive index minus the third refractive index, and the firstdifference is larger than the second difference. In a particularembodiment, the first refractive index and the third refractive indexare substantially the same.

In another particular embodiment, the substrate includes a fourth layerhaving a fourth refractive index, and the fourth layer is opticallycoupled to the first layer, the second layer, and the third layer. In amore particular embodiment, a third difference is an absolute value ofthe first refractive index minus the fourth refractive index, and thethird difference is larger than the second difference. In another moreparticular embodiment, the third refractive index has a value that is 90to 110% of the first refractive index, and each of the second and fourthrefractive indices is less than 90% of the first refractive index. Instill another more particular embodiment, each of the first and thirdrefractive indices has a value in a range of approximately 1.8 to 3.0,and each of the second and fourth refractive indices has a value in arange of approximately 1.4 to 1.8.

In still another embodiment of the first aspect, the first structure hasa second edge, wherein the first layer overlies the second edge. In aparticular embodiment, the first edge of the second structure includes areceding edge, wherein the receding edge overlies the second edge of thefirst structure.

In a further embodiment of the first aspect, the first structureincludes an electrode for the electronic device. In another furtherembodiment, the second layer includes an organic active layer. In stillanother further embodiment, the electronic device includes a display,wherein the first layer, the first edge, and the second layer lie withinan array of the display. In yet another further embodiment, the secondstructure does not have an upper portion that is spaced apart andoverhangs a lower portion of the second structure, wherein the lowerportion lies between the upper portion and the substrate.

In a second aspect, an electronic device includes a substrate, and afirst structure overlying the substrate. The first structure includes afirst layer having a perimeter and a pattern lying within the perimeter,and the pattern extends at least partly though the first layer to definean opening with a first edge. The electronic device also includes asecond structure overlying the opening and at least portions of thefirst structure and the substrate. The second structure includes asecond layer that includes a second edge. The electronic device stillfurther includes a third layer overlying at least portions of the firststructure and the second structure. The third layer includes a firstportion and a second portion, the first portion of the third layeroverlies the first structure and the second structure at the secondedge, and the second portion of the third layer overlies the firststructure but not the second structure.

In one embodiment of the second aspect, the first structure includes anelectrode. In a particular embodiment, the second structure includes awell structure.

In another embodiment of the second aspect, the first layer has a firstrefractive index, the second layer has a second refractive index, andthe third layer has a third refractive index. A first difference is anabsolute value of the first refractive index minus the second refractiveindex, and a second difference is an absolute value of the firstrefractive index minus the third refractive index. The first differenceis larger than the second difference. In a particular embodiment, thefirst refractive index and the third refractive index are substantiallythe same. In another particular embodiment, each of the first and thirdrefractive indices has a value in a range of approximately 1.8 to 3.0,and the second refractive index has a value in a range of approximately1.4 to 1.8.

In still another embodiment of the second aspect, the third layeroverlies the first edge. In a further embodiment, the second edge of thesecond structure includes a receding edge, wherein the receding edgeoverlies the first edge of the first structure. In another furtherembodiment, the third layer includes an organic active layer. In stillanother further embodiment, the electronic device includes a display,wherein the first structure, first edge, second structure, the secondedge, and the third layer lie within an array of the display.

In a third aspect, a process for forming an electronic device includesforming a first structure over a substrate, wherein the first structureis an electrically active structure. The process also includes forming asecond structure over at least portions of the first structure and thesubstrate. The second structure includes a first layer, the first layerhas a first refractive index, and the first layer includes a first edge.The process further includes forming a second layer overlying the firststructure and the second structure. The second layer has a secondrefractive index that is lower than the first refractive index, thesecond layer includes a first portion and a second portion, the firstportion of the second layer overlies the first structure at the firstedge of the first layer and overlies the second structure, and thesecond portion of the second layer overlies the first structure but notthe second structure.

In one embodiment of the third aspect, forming the second structureincludes depositing the first layer, and patterning the first layer,wherein

-   the first edge includes a receding edge after patterning. In another    embodiment, forming the second structure includes deposing the first    layer using a precision deposition technique, such that the second    structure is formed as the first layer is deposited.

In still another embodiment of the third aspect, the first structureincludes a third layer lying between a user side of the electronicdevice and each of the second structure and the second layer. In aparticular embodiment, the third layer has a third refractive index. Afirst difference is an absolute value of the first refractive indexminus the second refractive index, a second difference is an absolutevalue of the first refractive index minus the third refractive index,and the first difference is larger than the second difference. Inanother particular embodiment, the first refractive index and the thirdrefractive index are substantially the same. In still another particularembodiment, the first structure includes an electrode, and the secondstructure includes a well structure. In a further particular embodiment,each of the first and third refractive indices has a value in a range ofapproximately 1.8 to 3.0, and the second refractive index has a value ina range of approximately 1.4 to 1.8.

In a further embodiment of the third aspect, the second layer includesan organic active layer. In another further embodiment, the secondstructure does not have an upper portion that is spaced apart andoverhangs a lower portion of the second structure, wherein the lowerportion lies between the upper portion and the substrate.

Other features and advantages of the invention will be apparent from thefollowing detailed description, and from the claims. The detaileddescription first addresses Definitions and Clarification of Termsfollowed by Refraction, Reflection, and Waveguides, Halo Effect,Fabrication Process, Device Operation and Halo Effect, Other Shapes andPatterns, Other Embodiments, Advantages, and finally Examples.

1. Definitions and Clarification of Terms

Before addressing details of embodiments described below, some terms aredefined or clarified.

The term “active” when referring to a layer or material is intended tomean a layer or material that exhibits electro-radiative orelectromagnetic properties. An active layer material may emit radiationor exhibit a change in concentration of electron-hole pairs whenreceiving radiation.

The terms “array,” “peripheral circuitry,” and “remote circuitry” areintended to mean different areas or components of an electronic device.For example, an array may include pixels, cells, or other structureswithin an orderly arrangement (usually designated by columns and rows).The pixels, cells, or other structures within the array may becontrolled locally by peripheral circuitry, which may lie on the samesubstrate as the array but outside the array itself. Remote circuitrytypically lies away from the peripheral circuitry and can send signalsto or receive signals from the array (typically via the peripheralcircuitry). The remote circuitry may also perform functions unrelated tothe array. The remote circuitry may or may not reside on the substratehaving the array.

The term “buffer layer” or “buffer material” is intended to meanelectrically conductive or semiconductive materials that may have one ormore functions in an organic electronic device, including but notlimited to, planarization of the underlying layer, charge transportand/or charge injection properties, scavenging of impurities such asoxygen or metal ions, and other aspects to facilitate or to improve theperformance of the organic electronic device. Buffer Materials may bepolymers, solutions, dispersions, suspensions, emulsions, colloidalmixtures, or other compositions.

The term “charge-blocking,” when referring to a layer, material, member,or structure, is intended to mean such layer, material, member orstructure reduces the likelihood that a charge migrates into anotherlayer, material, member or structure.

The term “charge carrier,” with respect to an electronic component orcircuit, is intended to mean the smallest unit of charge. Chargecarriers can include n-type charge carriers (e.g., electrons ornegatively charged ions), p-type charge carriers (e.g., holes orpositively charged ions), or any combination thereof.

The term “charge-injecting,” when referring to a layer, material,member, or structure, is intended to mean such layer, material, memberor structure promotes charge migration into an adjacent layer, material,member or structure.

The term “charge-transport,” when referring to a layer, material,member, or structure is intended to mean such layer, material, member,or structure facilitates migration of such charge through the thicknessof such layer, material, member, or structure with relative efficiencyand small loss of charge. [see “electron transport”, “hole transport.”]

The term “electrically active structure” is intended to mean a structurewithin a radiation-emitting component, a radiation-responsive component,or a combination thereof, wherein such structure is designed such that asignificant amount of charge carriers flow through, into, or out of suchstructure during normal operation of such radiation-emitting component,radiation-responsive component, or combination thereof. An example of anelectrically active structure includes an anode, a cathode, a portion ofan organic active layer, a buffer layer, a charge-blocking layer, acharge-injecting layer, a charge-transport layer, or any combinationthereof.

The term “environmental protection structure” is intended to mean astructure that substantially protects a portion of an electronic devicefrom damage originating from a source external to the electronic device.An example of an environmental protection structure includes asubstrate, a lid attached to the substrate, or a combination thereof.

The term “layer” refers to a film covering a desired area. The area canbe as large as an entire display, or as small as a specific functionalarea, such as a single sub-pixel. A layer can be made from one or moreorganic or inorganic materials or mixtures thereof.

The term “organic active layer” is intended to mean one or more organiclayers, wherein at least one of the organic layers, by itself, or whenin contact with a dissimilar material is capable of forming a rectifyingjunction.

The term “over-hanging projection” is intended to mean a portion of astructure overlying a substrate, wherein that portion, as seen from across-sectional view along a line substantially perpendicular to aprimary surface of a substrate, extends over and is spaced apart fromanother portion of the same structure. Such spaced-apart portions of thestructure may be part of the same or different layers.

The term “precision deposition technique” is intended to mean adeposition technique that is capable of depositing one or more materialsover a substrate at a dimension, as seen from a plan of the substrate,no greater than approximately one millimeter. A stencil mask, frame,well structure, patterned layer or other structure(s) may or may not bepresent during such deposition.

The term “primary surface” is intended to mean a surface of a substratefrom which an electronic device is subsequently formed.

The term “radiation-emitting component” is intended to mean anelectronic component, which when properly biased, emits radiation at atargeted wavelength or spectrum of wavelengths. The radiation may bewithin the visible-light spectrum or outside the visible-light spectrum(ultraviolet (“UV”) or infrared (“IR”)). A light-emitting diode is anexample of a radiation-emitting component.

The term “radiation-responsive component” is intended to mean anelectronic component can sense or otherwise respond to radiation at atargeted wavelength or spectrum of wavelengths. The radiation may bewithin the visible-light spectrum or outside the visible-light spectrum(UV or IR). Photodetectors, IR sensors, biosensors, and photovoltaiccells are examples of radiation-responsive components.

The term “receding edge” is intended to mean an edge of a layer orstructure, wherein a thickness of the layer or structure gradually getsthinner near a distal point of the edge. A beveled edge, a concave edge,a convex edge, or the like is an example of a receding edge. Asquared-off edge is not a receding edge.

The term “substrate” is intended to mean a base material that can beeither rigid or flexible and may be include one or more layers of one ormore materials, which can include, but are not limited to, glass,polymer, metal or ceramic materials or combinations thereof.

The term “user side” is intended to mean a side of the electronic deviceprincipally used during normal operation of the electronic device. Inthe case of a display, the side of the electronic device seen by a userwould be a user side. In the case of a detector or voltaic cell, theuser side would be the side that principally receives radiation that isto be detected or converted to electrical energy. Note that anelectronic device may have more than one user side.

The term “well structure” is intended to structure that provideselectrical insulation between adjacent electrodes, wherein at least partof the electrodes lie at a common elevation above the primary surface ofthe substrate.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

Additionally, for clarity purposes and to give a general sense of thescope of the embodiments described herein, the use of the “a” or “an”are employed to describe one or more articles to which “a” or “an”refers. Therefore, the description should be read to include one or atleast one whenever “a” or “an” is used, and the singular also includesthe plural unless it is clear that the contrary is meant otherwise.

Group numbers corresponding to columns within the Periodic Table of theelements use the “New Notation” convention as seen in the CRC Handbookof Chemistry and Physics, 81^(st) Edition (2000).

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although suitable methods andmaterials are described herein for embodiments of the invention, ormethods for making or using the same, other methods and materialssimilar or equivalent to those described can be used without departingfrom the scope of the invention. All publications, patent applications,patents, and other references mentioned herein are incorporated byreference in their entirety. In case of conflict, the presentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting.

Other features and advantages of the invention will be apparent from thefollowing detailed description, and from the claims.

To the extent not described herein, many details regarding specificmaterials, processing acts, and circuits are conventional and may befound in textbooks and other sources within the organic light-emittingdiode display, photodetector, photovoltaic, and semiconductor arts.

2. Refraction, Reflection, and Waveguides

The waveguide effect is better understood with respect to FIG. 1. Whilethe discussion of FIG. 1 is directed to light, other types of radiationmay have similar effects. Note that the specificity in the materials andrefractive indices given with respect to FIG. 1 are to simplifyunderstanding of refraction and the waveguide effect and is not intendedto limit the present invention. In FIG. 1, air 102 (η=1.0) lies adjacentto a first layer 104 (e.g., indium titanium oxide (“ITO”), η=2.0), asecond layer 106 (e.g., organic active layer, η=1.6), and a cathode 108,which for the purposes of this discussion is considered a mirror.Interfaces 122, 124, and 126 lie between different pairs of the layers.

Radiation is emitted in a plurality of directions from a radiationemission site 142. At the interfaces 122, 124, and 126 between layers,radiation may pass from one layer into another, be reflected at theinterface, or both. Because the cathode 108 is a mirror, essentially alllight reaching interface 126 is reflected by the cathode 108. Whetherany or all of the radiation is reflected at interfaces 122 and 124depends on the refractive indices of the layers at the interface and theincident angle of the radiation, which is the approach angle for theradiation as measured from a line perpendicular to the interface.Referring to FIG. 1, an incident angle of 0° corresponds to radiationpropagating in a direction along a vertical axis. If the incident angleis larger than a critical angle, at least some of the radiation isreflected at the interface. If the incident angle is the same or lessthan the critical angle, substantially all of the radiation passesthrough the interface. The critical angle (θ_(c)) is given by Equation1.θ_(c)=sin⁻¹(η₂/η₁)  Equation 1

wherein:

η₁ is the refractive index of a first layer or material in which theradiation is propagating; and

η₂ is the refractive index of a second layer or material lying on theother side of the interface of the first layer or material.

Radiation 162, 164, and 166 are emitted from emission site 142.Radiation 162 propagates in a direction substantially perpendicular tointerfaces 124 and 122. Therefore, substantially all of the radiationpasses into the air 102 without any refraction. Radiation 164 isinitially reflected by the cathode 108 at interface 126. Radiation 164propagates through the second layer 106 and reaches interface 124 at anangle less than the critical angle but higher than 0°. Radiation 164 isrefracted as it propagates through the interface 124. Radiation 164propagates through the first layer 104 and reaches interface 122 at anangle less than the critical angle but higher than 0°. Radiation 164 isrefracted as it propagates through the interface 122.

Radiation 166 illustrates the waveguide effect. Radiation 166 reachesinterface 124, the incident angle is greater than the critical angle.Therefore, some of the radiation is reflected by the interface 124, asillustrated by radiation 169. However, because the refractive index ofthe second layer 106 (η=1.6) is lower than the refractive index of thefirst layer 104 (η=2.0), some of the radiation 166 enters the firstlayer 104, as illustrated by radiation 168. Radiation 169 continues topropagate within the second layer 106 in a manner similar to radiation166.

Radiation 168 propagates through the first layer 104 until it reachesinterface 122. Because the incident angle of radiation 168 at interface122 is greater than the critical angle, radiation 168 is reflected byinterface 122. Because the refractive index of the first layer 104(η=2.0) is greater than air 102 (η=1.0), substantially all of theradiation 168 is reflected at the interface 122. Radiation 168 continuesto propagate through the first layer 104 until it reaches the interface124 with the second layer 106. Similar to radiation 168 at interface122, because the incident angle of radiation 168 at interface 124 isgreater than the critical angle, radiation 168 is reflected by interface124. Because the refractive index of the first layer 104 (η=2.0) isgreater than the second layer 106 (η=1.6), substantially all of theradiation 168 is reflected at the interface 124.

As can be seen, radiation 166 is propagating laterally within layers 104and 106 via radiation 168 and 169. The radiation from radiation 166 iseffectively trapped and propagates laterally, which is usuallyundesired.

3. Halo Effect

The inventors have discovered a way to harness at least some of theradiation propagating laterally and redirect it in a direction moretowards the user of the device. By interfering with the waveguideeffect, the inventors have taken what is generally considered anunproductive and undesired effect to produce a beneficial phenomenonthat typically manifests itself as a halo surrounding aradiation-emitting component (e.g., an OLED). The intensity of theradiation emitting within the halo may be higher than the intensity ofradiation emitting within the center of a radiation-emitting component.

Although the mechanism and physical effects are not fully understood,the halo effect may occur when a first layer having an edge is coveredby a second layer, wherein the second layer overlies the edge and therefractive index of the second layer is lower than the refractive indexof the first layer.

By producing the halo effect, more radiation may be received by a userof the electronic device without an increase in driving voltage for theradiation-emitting component. More emission area is possible withoutincreasing the size of the radiation-emitting component.

While much of the discussion herein is directed towardsradiation-emitting components, similar effects may occur forradiation-responsive components. The use of the designs described hereinmay be used to increase the effective reception area of aradiation-responsive component without increasing the actual size of theradiation-responsive component.

4. Fabrication Process

Attention is now directed to details for a first set of embodiments thatis described and illustrated in FIGS. 2 to 12 in which a halo effect canbe seen with pixels. Materials currently used in forming the organicelectronic devices can be used. Therefore, process development andintegration concerns with new materials may be avoided.

The embodiment as illustrated in FIGS. 2 to 12 may be used for making amonochromatic passive matrix OLED display. Modifications that may bemade for use with multi-color or full-color passive matrix and activematrix OLED displays are described later in this specification.

FIG. 2 includes a plan view of a portion of a substrate 20. Morespecifically, FIG. 2 includes a portion of an array for a display.Peripheral and remote circuitry are not illustrated to simplify theunderstanding of the invention. Such peripheral and remote circuitry maybe formed before formation of the array, during formation of the array,after formation of the array, or any combination thereof. The substrate20 can include nearly any type and number of materials includingorganic, inorganic, conductive, semiconductive, or insulating materials.The materials and thicknesses of materials are conventional. If thesubstrate 20 lies along a user side of the electronic device, thesubstrate 20 should be capable of transmitting at least 70% of theradiation propagating normal to the surface of the substrate 20 alongthe user side. Depending on the material(s) selected for the substrate20, each of the materials may have a refractive index in a range ofapproximately 1.4 to 1.8. Glass and many types of plastics used insubstrates have refractive indices in a range of approximately 1.5 to1.6.

After reading this specification, skilled artisans appreciate that theselection of material(s) that can be used for the substrate 20 varieswidely. After reading this specification, skilled artisans are capableof selecting the appropriate material(s) based on their physical,chemical, and electrical properties. For simplicity, the material(s)used for this base are referred to as substrate 20.

First electrodes 22 may then be formed over a primary surface 202 of thesubstrate 20 as illustrated in FIGS. 2 and 3. The first electrodes 22,which are a specific type of electrically active structure, can includenearly any conductive material. In this specific embodiment, the firstelectrodes 22 act as anodes for the electronic device being formed. Ingeneral, the material of the first electrodes 22 has a work functionrelatively higher than subsequently formed second electrodes that act asthe cathodes. A plurality of layers may be formed to create the firstelectrodes 22. One or more of the layers within the first electrodes 22can have a refractive index in a range of approximately 1.8 to 3.0. Inone particular embodiment, the first electrodes 22 include layers ofsilicon nitride 222 and ITO 224. Silicon nitride 222 can have arefractive index in a range of approximately 1.9 to 2.4 depending on thedeposition conditions. The ITO 224 may have a refractive index ofapproximately 2.0. In one specific embodiment, the silicon nitride 222and ITO 224 may have refractive indices that are substantially the same,such as approximately 2.0.

In the embodiment illustrated in FIGS. 2 and 3, the first electrodes 22lie between a user side 204 of the electronic device and thesubsequently formed organic active layer. Therefore, first electrodes 22should be transparent to allow the radiation to be transmitted throughthe first electrodes 22. Additionally, at least one of the layers withinthe first electrodes 22 has a refractive index higher than the materialwithin the substrate 20 along the primary surface 202 of the substrate20. Exemplary materials include ITO, zirconium tin oxide (“ZTO”),elemental metals, metal alloys, and combinations thereof. ITO and ZTOmay be thicker when used as the first electrodes 22 and still allowsufficient transmission of radiation. For example, when ITO or ZTO areused as the first electrode 22, the first electrodes 22 may have athickness in a range of approximately 100 to 200 nm. More specifically,the thickness of the silicon nitride layer 222 can be in a range ofapproximately 50 to 1000 nm, and thickness of the ITO layer 224 can bein a range of approximately 50 to 150 nm. The first electrodes 22 areformed using a conventional technique.

One or more well structures 42 may be formed as illustrated in FIGS. 4and 5. The well structures 42 include edges 44 that define where theradiation-emitting components will be formed. In one embodiment, thewell structures 42 are not electrically active structures. The wellstructures 42 include one or more layers of material(s) that arerelatively inert to subsequent processing, not opaque to the radiation,and are electrically insulating. Some non-limiting exemplary materialsinclude radiation imaginable materials (e.g., photoresists, includingpositive acting (Novolac) and negative acting, polyimide, etc.), siliconnitride, silicon oxide (including silicon dioxide, siloxanes, spin-onglass, etc.), undoped or lightly doped silicon, metal oxides, metalnitrides, metal oxynitrides, and combinations thereof. In oneembodiment, the material(s) may be transparent to radiation emitted bythe radiation-emitting component, and in another embodiment, thematerial(s) may be translucent to radiation emitted by theradiation-emitting component. In still another embodiment, the wellstructures 42 define areas where portions of an organic layer will beformed. The well structures 42 may help to keep different materials oforganic layers away from one another. In one embodiment, the wellstructures can help to keep red and green light-emitting materials fromentering the area for a blue light-emitting component. The wellstructures may also help to electrically insulate the first electrodes22 from one another. Each layer within the well structures 42 caninclude an organic material, an inorganic material, or a combinationthereof. One or more of the layers within the well structures 22 canhave a refractive index in a range of approximately 1.8 to 3.0. In oneembodiment, one or more layers within the first electrodes 22 have arefractive index that is in a range of approximately 90 to 110% of arefractive index of one or more layers within the well structure 42. Inone specific embodiment, the well structures 42 may be made from a layerof polyimide, and the first electrodes 42 may include silicon nitride222 and ITO 224. For this specific embodiment, all layers within thewell structures 42 and first electrodes 22 may have substantially thesame refractive index, namely 2.0.

The well structures 42 may be formed by depositing layer(s) ofmaterial(s) and then patterning those layer(s) or by forming the patternas the layer(s) for the well structures 42 is deposited. For thepurposes of this specification, deposition is to be construed broadly toinclude liquid or vapor deposition techniques used in themicroelectronics art (OLED, flat panel, semiconductor and other similararts). After the well structures 42 are formed, they have an edge 44,which in this embodiment is a concave edge that forms a dome-shapedstructure.

FIG. 6 includes an enlarged view of a portion of FIG. 5 to show betterthe relationships of the different parts of the electronic device atthis point in the process. In one embodiment, the height (thickness) 64of the well structure 42 is at least as thick as a combined thickness ofthe first electrodes 22 and the subsequently formed organic layer. Inanother embodiment, the height 64 is in a range of approximately 0.5 to10.0 microns. In another embodiment, the height may be in a range ofapproximately 1.0 to 3.0 microns. As previously pointed out, the wellstructure has a concave edge 44. The distance 62 from an end 442 of thewell structure 42 to a closest point where the well structure 42 has asubstantially flat upper surface may be in a range of approximately 1 to10 microns. In one specific embodiment, the height 64 is approximately2.0 microns, and the distance 62 is approximately 5.0 microns.

FIGS. 7 to 9 illustrate other potential shapes for edges of the wellstructures 42. FIG. 7 includes a beveled edge 74, FIG. 8 includes aconvex edge 84, and FIG. 9 includes a step-function edge 94. Edges 44,74, and 84 are examples of receding edges, in that the thickness of thewell structure 42 becomes gradually thinner near the ends 442, 742, or842 over the first electrodes 22. Step-function edge 94 does not have areceding edge. Note that each of the edges 44, 74, 84, and 94 can helpto break up the waveguide effect within a subsequently formed organiclayer and allow more radiation to be emitted along the user side 204 ofthe electronic device. A receding edge may be more efficient at emittingradiation as compared to the step-function edge 94. In one embodiment,the edge of the first electrodes 22 underlies the receding edge (edge44, 74, 84).

A few, non-limiting methods are described regarding how to achieve theedges 44, 74, 84, and 94. After reading this specification, skilledartisans will appreciate that many other methods are possible.

In one embodiment, edges 44 may be obtained by depositing one or morelayers of material(s) and patterning the layer(s) using a conventionaltechnique. The patterned layer may be subjected to an elevatedtemperature (i.e., higher than room temperature) such that corners ofthe pattern are rounded to obtain the edges 44. The corner rounding maybe referred to as a reflow process. In one specific embodiment,photoresist is the material, and the temperature for the reflow is in arange of approximately 100 to 250° C. for a time period in a range ofapproximately 1 to 10 minutes. In another specific embodiment,borosilicate glass is the material, and the temperature for the reflowis in a range of approximately 400 to 700° C. for a time period in arange of approximately 10 to 30 minutes. The reflow process is notsignificantly affected by pressure, and therefore, the reflow may beperformed at approximately atmospheric pressure. The rounding to formthe edges 44 is a function of the material, time and temperature. Forany particular material, as the time, temperature, or both are too low,the degree of rounding may be insufficient. If the time, temperature, orboth are too high, too much of the well structure 42 may flow over thefirst electrodes 22 and reduce pixel size, or in a worse case, not allowa pixel to be properly formed (e.g., form an electrical open between theelectrodes of the pixel).

In another embodiment, the edges 44 may be obtained by depositing alayer using a precision deposition technique, such as printing (e.g.,ink-jet printing or screen printing). After depositing, a solvent withinthe material may be evaporated. The edges 44 may be formed as depositedor may be obtained during the solvent evaporation activity. If the edges44 need further rounding, then a reflow process, such as the onepreviously described may be used. In still another embodiment, a stencilmask may be used so that the layer is only deposited where the wellstructures are to be formed. A reflow process may be used if furthercorner rounding is needed.

Referring to FIG. 7, the beveled edges 74 may be obtained using a resisterosion process. Resist erosion processes are conventional within thesemiconductor arts to form contact openings. After depositing the layerfor the well structures 42 over all the array, a patterning resist layer(not shown) is formed over the layer for the well structures 42. In oneembodiment, the edge of the resist layer corresponds to the end 742. Anetching technique is performed to removing portions of the layer for thewell structures 42 from over the first electrodes 22. While the layerfor the well structures 42 is being etched, the resist is being etchedin a lateral direction to increase the size of the opening in the resistlayer. In one embodiment, the resist layer includes an organic material,and oxygen can be used in the etching gas to etch the resist layer. Ifthe layer for the well structures 42 includes silicon nitride, theetching gas may include fluorine-containing species (e.g., fluorinatedmethane or ethane (CF₄, CHF₃, C₂F₆, C₂F₄H₂, etc.), SF₆, NF₃, F₂, andcombinations thereof) and an oxygen-containing species (e.g., O₂, O₃, orthe like). The slope of the beveled edges 74 may be adjusted by changingthe ratio of fluorine atoms to oxygen atoms within the etching gas. Asthe ratio of fluorine atoms to oxygen atoms in the etching gasincreases, the beveled edge 74 will be steeper (closer to a verticaledge), and as the ratio of fluorine atoms to oxygen atoms in the etchinggas decreases, the beveled edge 74 will have a shallower angle (whenusing the primary surface 204 as a reference plane). Any remainingportion of the resist layer can be removed using a conventionaltechnique.

Referring to FIG. 8, the convex edges 84 can be obtained using anisotropic etching technique. A resist layer (not shown) is formed andpatterned similar to an embodiment described with respect to the bevelededges 74. In one embodiment, the edge of the resist layer corresponds tothe end 842. However, unlike an embodiment described with respect toFIG. 7, in this embodiment, the resist layer may not be significantlyetched. The etch may be performed using wet chemical etching or dryetching technique. In one embodiment, the etchant used for the isotropicetching etches the layer of the well structures 42 selectively to theresist layer and the material of the uppermost layer of the firstelectrodes 22. After etching, the resist layer can be removed using aconventional technique.

Referring to FIG. 9, the step-function edges 94 can be obtained using ananisotropic etching technique. A resist layer (not shown) is formed andpatterned similar to an embodiment described with respect to the bevelededges 74. Similar to the embodiment described with respect to FIG. 8, inthis embodiment, the resist layer may not be significantly etched. Theetch may be performed using a dry etching technique. In one embodiment,the etchant used for the anisotropic etching etches the layer of thewell structures 42 selectively to the resist layer and the material ofthe uppermost layer of the first electrodes 22. The anisotropic etchinghelps to transfer the edge of the resist layer into the layer for thewell structures 42. After etching, the resist layer can be removed usinga conventional technique.

In another embodiment, the edges 94 may be obtained by depositing alayer using a precision deposition technique, such as printing (e.g.,ink-jet printing or screen printing). After depositing, a solvent withinthe material may be evaporated. In still another embodiment, a stencilmask may be used so that the layer is only deposited where the wellstructures 42 are to be formed. In one embodiment, the stencil mask maybe used with a vapor deposition technique. Unlike an embodiment of FIG.7, a reflow process may be not be required.

After the well structures 42 have been formed, an organic layer 100 isformed as illustrated in FIG. 10. The organic layer 100 may include oneor more layers. For example, the organic layer 100 may include ahole-transport layer 102 and an organic active layer 104, or the organicactive layer 104 without the hole transport layer 102. Although notshown, the organic layer 100 may include an electron-transport layer. Itis further understood that organic layer 100 in organic electronicdevices may include a variety of organic materials, such as chargetransport materials, anti-quenching materials, a variety of activematerials (e.g. light-emitters, photodetectors, IR detectors and otherradiation sensitive materials).

The hole-transport layer 102 and the organic active layer 104 are formedsequentially over the first electrodes 22 and at least portions of thewell structures 42. Each of the hole-transport layer 102 and the organicactive layer 104 can be formed by using a liquid deposition technique todeposit appropriate materials as described below. One or both of thehole-transport layer 102 and the organic active layer 104 may be curedafter it is applied. In one embodiment, the organic layer 100 overliesall of first electrodes 22 and the well structures 42. In an alternativeembodiment, the organic layer 100 lies within the openings of the wellstructures 42 and along only a portion of the well structures 42 nearthe edges 44, 74, 84, or 94. In this embodiment, a precision depositiontechnique, such as ink-jet printing, may be used to dispense a smallamount of the organic layer, such that the organic layer 100 isdiscontinuous between the radiation-emitting components. In anotherembodiment, the hole-transport layer 102 may be formed over all of thewell structures 42 within the array, but the organic active layer 104may only be formed within the openings of the well structures 42 and mayor may not overlap onto edges 44, 74, 84, or 94 of the well structures42.

In one embodiment, the hole-transport layer 102 can include an organicpolymer, such as polyaniline (“PANI”), poly(3,4-ethylenedioxythiophene)(“PEDOT”), or an organic charge transfer compound, such astetrathiafulvalene tetracyanoquinodimethane (TTF-TCQN). Thehole-transport layer 104 typically has a thickness in a range ofapproximately 100 to 250 nm.

The composition of the organic active layer 104 typically depends uponthe application of the electronic device. When the organic active layer104 is used in a radiation-emitting electronic device, the material(s)of the organic active layer 104 will emit radiation when sufficient biasvoltage is applied to the anode and cathode. The radiation-emittingactive layer may contain nearly any organic electroluminescent or otherorganic radiation-emitting materials.

Such materials can be small molecule materials or polymeric materials.Small molecule materials may include those described in, for example,U.S. Pat. No. 4,356,429 and U.S. Pat. No. 4,539,507. Alternatively,polymeric materials may include those described in U.S. Pat. No.5,247,190, U.S. Pat. No. 5,408,109, and U.S. Pat. No. 5,317,169.Exemplary materials are semiconducting conjugated polymers. An exampleof such a polymer is poly(phenylenevinylene) referred to as “PPV.” Thelight-emitting materials may be dispersed in a matrix of anothermaterial, with or without additives, but typically form a layer alone.The organic active layer generally has a thickness in the range ofapproximately 40 to 100 nm.

When the organic active layer 104 is incorporated into aradiation-responsive electronic device, the material(s) of the organicactive layer 104 may include many conjugated polymers andelectroluminescent materials. Such materials include for example, manyconjugated polymers and electro-and photo-luminescent materials.Specific examples includepoly(2-methoxy,5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene) (“MEH-PPV”)and MEH-PPV composites with CN-PPV. The organic active layer 104typically has a thickness in a range of approximately 50 to 500 nm.

Although not shown, an optional electron-transport layer may be formedover the organic active layer 104. In one specific embodiment, theelectron-transport layer can include metal-chelated oxinoid compounds(e.g., Alq₃); phenanthroline-based compounds (e.g.,2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (“DDPA”),4,7-diphenyl-1,10-phenanthroline (“DPA”)); azole compounds (e.g.,2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole (“PBD”),3-(4-biphenyl)₄-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole (“TAZ”); orany one or more combinations thereof. Alternatively, the optionalelectron-transport layer may be inorganic and include BaO, LiF, or Li₂O.The electron-transport layer typically has a thickness in a range ofapproximately 30 to 500 nm.

In one embodiment, each of the layers within the organic layer 100 mayhave a refractive index in a range 1.4 to 1.8. In one particularembodiment, each of the hole-transport layer 102 and organic activelayer 104 have a refractive index of approximately 1.6.

Second electrodes 112 are formed over openings within the wellstructures 42 and portions of the first electrodes 22, well structures42, and organic layer 100 as illustrated in FIGS. 11 and 12. The secondelectrodes 112 act as cathodes for the electronic device. In oneembodiment, the second electrodes 112 can include a metal-containinglayer having a low work function, which is lower than the firstelectrodes 22 that have a high work function. Materials for the secondelectrodes 112 can be selected from Group 1 metals (e.g., Li, Cs), theGroup 2 (alkaline earth) metals, the rare earth metals including thelanthanides and the actinides. The second electrodes 112 have athickness in a range of approximately 300 to 600 nm. In one specific,non-limiting embodiment, a Ba layer of less than approximately 10 nmfollowed by an Al layer of approximately 500 nm may be deposited. Astencil mask corresponding to the pattern of the second electrodes 112can be used with a conventional deposition process, such as evaporation,sputtering, or the like. For simplicity, the second electrodes 112 areconsidered an optical mirror.

Other circuitry not illustrated in FIGS. 2 to 12 may be formed using anynumber of the previously described or additional layers. Although notshown, additional insulating layer(s) and interconnect level(s) may beformed to allow for circuitry in peripheral areas (not shown) that maylie outside the array. Such circuitry may include row or columndecoders, strobes (e.g., row array strobe, column array strobe), orsense amplifiers.

An encapsulating layer (not shown) can be formed over the array and theperipheral and remote circuitry to form a substantially completedelectrical component, such as an electronic display, a radiationdetector, and a voltaic cell. The encapsulating layer may be attached tothe substrate 20. Radiation may be transmitted through the encapsulatinglayer. If so, the encapsulating layer should be transparent to theradiation.

In one embodiment, the electronic device comprises one or moreradiation-emitting components, one or more radiation-responsivecomponents, or any combination thereof. Within each of theradiation-emitting component(s) or radiation-responsive components,electrically active structures can include the first electrodes 22, thesecond electrodes 112, and portions of the organic layer 100 lyingbetween the first electrodes 22 and second electrodes 112. Chargecarriers can flow through the first electrodes 22, second electrodes112, or both. With respect to the organic layer 100, for aradiation-emitting component, charge carriers can flow into the organiclayer 100 from the first electrodes 22, second electrodes 112, or both,and radiation can be emitted from the organic layer 100. For aradiation-responsive component, radiation can be received by the organiclayer 100, thus producing charge carriers that can flow from the organiclayer 100 to the first electrodes 22, second electrodes 112, or both.For the purposes of this specification, a thin-film transistor is notconsidered an electrically active structure because it is not part of aradiation-emitting component (e.g., an OLED) or a radiation-responsivecomponent (e.g., radiation sensor or photovoltaic cell).

5. Device Operation and the Halo Effect

In one embodiment, a display is formed having an array ofradiation-emitting components. When the first and second electrodes 22and 112 are properly biased, the radiation-emitting components can emitradiation as illustrated in FIG. 13, which is a view from a user side ofthe electronic device. The actual size of the radiation-emittingcomponent 132 is defined by the openings within the well structures 42and generally corresponds to the inner solid ovals as seen in FIG. 13.Additional radiation can be emitted that appears to be halos 134 thatsurround the radiation-emitting components 132. As seen in FIG. 13, theemission intensity of the halos 134 is higher than the emissionintensity near the center of the radiation-emitting components 132. Inone embodiment, the emission intensity of the halos 134 is in a range ofapproximately 10 to 100% higher than the emission intensity near thecenter of the radiation-emitting components 132. The halos 134 increasethe amount of radiation seen by a user without an increase in power.

FIG. 14 includes a plot of radiation emission intensity as a function ofdistance. The edge of the well structure 42 (“PI edge”) is atapproximately 203 microns, and the edge of the first electrode 22 (“ITOedge”) is at approximately 198 microns. In other words, the wellstructure 42 overlaps the first electrode 22 by approximately fivemicrons. Referring to the “unaged” device, near the center of theradiation-emitting component (towards the right-hand side of FIG. 14),the intensity is approximately 140.

Closer to the edge of the well structure 42, the emission intensity isreduced to approximately 105. The emission intensity peaks within thehalos 134 at approximately 190, and the tails off. In FIG. 14, the peakemission intensity in the halo 134 is approximately 50% higher than nearthe center of the radiation-emitting component. At approximately 192microns, the emission intensity is only about 10% of the peak emissionintensity. Referring to the “aged 45 hrs” device, a similar effect isseen. The halo 134 has a peak with a higher intensity compared to thecenter of the radiation-emitting component. Still, the peak emissionintensity in the halo 134 is approximately 50% higher than near thecenter of the radiation-emitting component. However, the peak is lessintense (approximately 120) and the tail toward the left is less steep.To a user of the electronic device, the image would appear more blurredor “bleeding” with the electronic device “aged 45 hrs.” At 182 microns,the intensity is only about 10% of the peak intensity.

The width of the halo 134 may be a function of the shape at the edge ofthe well structure or any of its layer(s), the thickness(s) of theorganic layer 100, and age of the device. In one embodiment, the widthof the halo may be in a range of approximately 1 to 50 microns, and inanother embodiment, the width of the halo may be in a range ofapproximately 5 to 20 microns.

Although not fully understood and characterized, the halo 134 may berelated to the shapes (including thicknesses) and refractive indices ofthe layers and structures near the edges of the radiation-emittingcomponents. In one embodiment, the organic layer 100 overlaps onto atleast a portion of the layer within the well structures 42. Thedifference in elevation seen by the organic layer 100 may disrupt atleast part of the waveguide effect within the organic layer 100.Radiation may propagate along the planar portions of the organic layer100 and reach the well structures 42. Because the radiation may beincident with layer(s) within the well structures 42 at an angle lessthan the critical angle for those layer(s), radiation that wouldotherwise continue to propagate along the organic layer 100 may passinto the well structure 42. Also, to the extent other radiation wouldcontinue to propagate, the change in topography may change the angles atwhich the radiation propagates, so that the radiation may “bouncearound” the region where the organic layer 100 overlies edges oflayer(s) within the well structures 42. Reflections from the interfaces,including the interface between the organic layer 100 and the secondelectrodes 112, may eventually allow some of the radiation to exit theuser side of the electronic device.

The halo 134 may be related to layer(s) within the well structures 42overlapping over edges of layer(s) within the first electrodes 22. Theedges of the layer(s) within the first electrodes 22 may reflect someradiation towards the edges 44, 74, 84, or 94 of the well structures 22,which in turn, may reflect radiation, such that the radiation propagatesto interfaces of layer(s) within the first electrodes 22 at angles atless the critical angles. In one embodiment, the edge of the layer(s)within the first electrodes 22 underlie the receding edges of layer(s)within the well structures 42. In another embodiment, step-functionedges 94 of the well structures 42 overlie the first electrodes 22. Thepresence of the edges of the layers within the first electrodes 22 andwell structures 42 may change the angles of reflection along interfacesso that the radiation may “bounce around” the region where the wellstructures 42 overlie the first electrodes 22. Reflections from theinterfaces may eventually allow some of the radiation to exit the userside of the electronic device.

Numbers for the refractive indices has been previously given withrespect to layers previously described. Relative comparisons ofrefractive indices are given as they may also have an impact on theintensity for the halo effect. In one embodiment, the refractive index(indices) of one or more of the layer within the first electrodes 22 mayhave a value that is approximately 90 to 110% of one or more layerswithin the well structures 42. The refractive indices of one or morelayers within the substrate 20 and the first electrodes 22 may be lessthan 90% of the refractive index of one or more layers within the wellstructures 42. In one specific embodiment, the substrate 20 includesglass (η approximately 1.5), the first electrodes 22 include a siliconnitride layer 222 (η approximately 2.0) and an ITO layer 224 (ηapproximately 2.0), the well structures includes polyimide (ηapproximately 2.0), the hole-transport layer 102 includes PEDOT (ηapproximately 1.6), and the organic active layer 104 includes apolyfluorene compound (n approximately 1.6).

In another embodiment, the refractive index of a layer within the wellstructures 42 is closer to the refractive index of a layer within thefirst electrodes 22 as compared to the refractive indices of thesubstrate 20 and organic layers 100. Put in other terms, a firstdifference is the absolute value of the refractive index of a layerwithin the well structures 42 minus the refractive index of a layerwithin the organic layer 100. A second difference is the absolute valueof the refractive index of a layer within the well structures 42 minusthe refractive index of a layer within the first electrodes 22. A thirddifference is the absolute value of the refractive index of a layerwithin the well structures 42 minus the refractive index of a layerwithin the substrate 20. Each of the first and third differences islarger than the second difference. If radiation is to be emitted throughthe encapsulating layer (e.g., lid), the refractive index of a layerwithin the encapsulating layer would be similar to that of the layerwithin the substrate 20. The substrate 20 and encapsulating layer may beparts of environmental protection structures.

In one specific embodiment, the refractive indices of the layers withinthe first electrodes 22 and well structures 42 are substantially thesame. In this embodiment, the interfaces between the first electrodes 22and well structures 42 may be nearly transparent to radiationpropagating between the first electrodes 22 and the well structures 42.Therefore, reflections at interfaces between the first electrodes 22 andwell structures 42 may have an insignificant impact on radiationreflected or entering well structures 42 at the edges 44, 74, 84, or 94and propagating towards the user side 204 of the electronic device.

The well structures 42 do not have overhanging projections, such asthose described in U.S. Patent Application Publication 2002/0060518 A1.If the well structures 42 were to have overhanging projections, thereflection of the radiation near the edge of the well structures 42 maybe adversely affected or otherwise have characteristics that vary fromelectronic device to electronic device due to variations in the shape ofthe overhanging projections.

6. Other Shapes and Patterns

FIGS. 15 to 17 illustrate another embodiment in which the firstelectrodes 151 include a pattern of slots 153 where radiation-emittingcomponents 155 are being formed. FIG. 16 includes an illustration alongsectioning line 16-16 in FIG. 15. In one embodiment, the firstelectrodes 151 includes layer 163. Within each radiation-emittingcomponent, the first electrode 151 can be seen to include slots 153 thatmay or may not extend through the entire thickness of the layer for thefirst electrode. In one specific embodiment, the first electrode 151includes an ITO layer 163. The thickness and formation of the ITO layer163 may be similar to one described for first electrodes 22 except thatthe silicon nitride layer is not present. The materials that can be usedfor the first electrodes 151 may be any of those previously describedfor the first electrodes 22. Well structures 171 are formed similar tothe process previously described with respect to well structures 42 asillustrated in FIGS. 4 to 6. Edges 173 have shapes similar to edges 44.In another embodiment, the well structures 171 may have edges similar toother embodiments previously described (e.g., FIGS. 7 to 9). Thefabrication process starting with the organic layer 100 is similar to aprior embodiment previously described.

The presence of the slots 153 within the radiation-emitting components151 may be used to help produce the halo effect within theradiation-emitting component itself rather than only near the perimeterof the radiation-emitting component. The widths of the slots 153 andremaining portions of the ITO layer 163 (adjacent to slots 153) withinthe radiation-emitting components 155 can be adjusted to achieve a highdegree of the halo effect. For example, the widths of the slots 153, thewidths of portions of the ITO layer 163 adjacent to the slots 153, orboth may be in a range of approximately 2 to 50 microns. Referring toFIG. 14, the peak intensity is about 4 microns from the edge of the wellstructures 42. In one embodiment, each of the widths for the slots 153and the potions of the ITO layer 163 between the slots may be in a rangeof approximately 5 to 15 microns. Note that the widths of the slots 153and widths of the portions of the ITO layer 163 adjacent to the slots153 may be the same or different. The slots 153 may have the same ordifferent widths compared to one another. Similarly, the portions of theITO layer 163 adjacent to the slots 153 may have the same or differentwidths compared to one another. The portions of the first electrodes 151between radiation-emitting components 155 electrically connect theradiation-emitting components 155 to one another, and in one embodimentincludes the ITO layer 163. The portions of the first electrodes 151between radiation-emitting components 155 may or may not be slotted.

The shapes of features within the first electrodes is not limited toslots. FIGS. 18 and 19 include an illustration where a checkerboardpattern may be used. In one embodiment, an active matrix display may beformed. Although not shown, the substrate 180 can include circuitry usedto drive the radiation-emitting components. In the embodiment, firstelectrodes 181 are not electrically connected to each other. Each of thefirst electrodes 181 includes a lower electrically conductive layer 183and an upper electrically conductive layer 185. The lower electricallyconductive layer 183 may have a thickness in a range of approximately 50to 500 nm, and provide an electrical connection between the upperconductive layer 185 and the underlying circuitry (not shown) within thesubstrate 180. The lower conductive layer 183 may have a pattern thatgenerally corresponds to the shape of the radiation-emitting component.The upper conductive layer 185 may include any of the electricallyconductive materials and thicknesses given for the first anodes 22previously described. In one embodiment, the upper conductive layer 185has a checkerboard pattern. Portions of lower conductive layer 183 canbe seen from a plan view where openings 193 lies between portions of theupper conductive layer 185. The well structures (not shown) can beformed using an embodiment as previously described. The rest of theelectronic device starting with the well structures can be formed usingany one or more of the embodiments previously described.

The checkerboard pattern as illustrated by FIGS. 18 and 19 has even moreexposed surface area along sides of the upper conductive layer 185compared to the slots 153 in FIGS. 15-17. In another alternativeembodiment, layer 163 or 185 may be etched only through a part of itsthickness.

In other embodiments, other shapes and other patterns may be used. Theshapes, patterns, or both can increase the exposed surface area in whichthe well structures contact, rather that only being limited to the edgenear the outer perimeter of the radiation-emitting component or wellstructure. Other shapes (e.g., circles, triangles, hexagons, etc. asseen from a plan view), other patterns, or a combination thereof may beused. After reading this specification, skilled artisans will be able todetermine what shapes, patterns, pitches, and spacings should be usedfor their particular applications.

7. Other Embodiments

In another embodiment, a full-color active matrix display may be formed.Portions of the organic active layer 104 may selectively receive organicdye(s) using an inkjet to allow the different colors within a pixel (acollection of radiation-emitting components) to be realized.Alternatively, different organic active layers may be used for thedifferent radiation-emitting components within a pixel. If an activematrix OLED display is being formed, thin-film circuits may be presentwith substrate 20. Such thin-film circuits are conventional.

In still other embodiments, the materials used for the first electrodes22 and second electrodes 112 can be reversed. In this manner, the anodesand cathodes are effectively reversed (cathode closer to the user side204 rather than the anode). Note that if the cathode lies closer to theuser side, it may need to be substantially transparent to radiationemitted or received by the electronic device. Similarly, note that theembodiment described within FIGS. 15 to 21 may also have the electrodesreversed.

At least some of the embodiments described herein may improve radiationemission characteristics without an increase in size of theradiation-emitting components or power. Additionally, optical cross talkbetween radiation-emitting components may be reduced. Designs can beachieved that take advantage of the waveguide effect and redirectradiation that may otherwise propagate to other components or outsidethe viewing area of the display to be emitted within the viewing area ofthe display. Concepts described herein can be used to potentially createradiation-responsive components that may be more sensitive to radiation.Note that one or more of the advantages are not required for allembodiments.

EXAMPLES

The invention will be further described in the following examples, whichdo not limit the scope of the invention described in the claims.

Example 1

This Example demonstrates that the effective aperture ratio (theemission area/radiation-emitting component area) can be larger than one.The process flow follows the process flow as previously described withrespect to FIGS. 2 to 12. After forming the first electrodes 22, aphotoresist layer (AZ 4110™ brand photoresist available from ClariantCorporation of Somerville, N.J., η approximately 2.0) is deposited to athickness of approximately two microns over ITO (η approximately 2.0) ofthe first electrodes. The photoresist layer is patterned using atechnique to produce a dome-type well structure, as seen from across-sectional view (both ends of topology). FIG. 5 includes anillustration of a similar electronic device at this point in the processflow. From a plan view of the electronic device, the well structures inExample 1 are different from FIG. 4. The well structures can includeopenings, such as lines, circles, and U-shaped openings. The shape ofthe well structure at the edge adjacent to the openings is similar tothat illustrated in FIG. 6. The organic active layer includes a greenlight-emitting polymer for the OLEDs. After fabrication is completed,the electronic device is operated so that the OLEDs formed emit greenlight. The image seen by a user along the user side of the electronicdevice is illustrated in FIG. 20. There is strong emission ring (alsocalled a “halo”) surrounding the pattern defined by first electrodes.This emission ring overlaps layer(s) within the well structures. FIG. 14illustrates the emission intensity distribution crossing the firstelectrode/well structure boundary. The emission intensity in the halo isapproximately 50% stronger than that in the radiation-emitting componentarea. The ring extends into the well structures by approximately 10microns. A reference device without the well structure can be made as areference. In this case, the shape of the emitter is defined by ITOpatterning. No emission ring (i.e., halo) near the edge of theradiation-emitting component is seen.

Example 2

This Example demonstrates that the halo effect is seen with other typesof electronic devices that emit other wavelengths of radiation. Anactive matrix OLED is made with radiation-emitting component size of 80radiation-emitting components per inch. The photoresist layer, such asthe one used in Example 1, is used for the well structures and is formedon the first electrodes. The photoresist layer is patterned to achievean oval shape. The topology of the photoresist layer near the edge isdome type, with tilted slope extending approximately 5 microns. SeeFIGS. 4 to 6. The organic active layer includes a blue light-emittingpolymer. The halo effect, similar to that seen with Example 1, can beobserved. A blue emission zone in the photoresist area can be seen alongthe user side of the electronic device. The intensity is stronger in thearea where the photoresist layer of the well structure overlaps thefirst electrode than near a center of the radiation-emitting component.The width of the ring is approximately 5 microns. With both effectivesize improvement and the stronger intensity in the ring area, the totallight output could be significantly higher than that without thepatterned photoresist layer within the well structure.

Example 3

This Example demonstrates that each of the halos correspond to theradiation emitted from the radiation-emitting component that itsurrounds. A full-color active matrix OLED display is made with a wellstructure surrounding each of the ITO anodes in the radiation-emittingcomponent area. The radiation-emitting component size is approximately85 micron by 255 micron. The well structures include openings that havean oval shape with width of approximately 60 microns. Emission rings ofthe same color can be observed surrounding each of the color pixels. Inother words, a red halo surrounds a red radiation-emitting component, agreen halo surrounds a green radiation-emitting component, and a bluehalo surrounds a blue radiation-emitting component. Therefore, the halois believed to originate from the radiation-emitting component itsurrounds rather than from other nearby radiation-emitting components.The width of the ring was approximately 5 micron.

Note that not all of the activities described above in the generaldescription or the examples are required, that a portion of a specificactivity may not be required, and that one or more further activitiesmay be performed in addition to those described. Still further, theorder in which activities are listed are not necessarily the order inwhich they are performed. After reading this specification, skilledartisans will be capable of determining what activities can be used fortheir specific needs or desires.

In the foregoing specification, the invention has been described withreference to specific embodiments. However, one of ordinary skill in theart appreciates that one or more modifications or one or more otherchanges can be made without departing from the scope of the invention asset forth in the claims below. Accordingly, the specification andfigures are to be regarded in an illustrative rather than a restrictivesense and any and all such modifications and other changes are intendedto be included within the scope of invention.

Any one or more benefits, one or more other advantages, one or moresolutions to one or more problems, or any combination thereof have beendescribed above with regard to one or more specific embodiments.However, the benefit(s), advantage(s), solution(s) to problem(s), or anyelement(s) that may cause any benefit, advantage, or solution to occuror become more pronounced is not to be construed as a critical,required, or essential feature or element of any or all the claims.

It is to be appreciated that certain features of the invention whichare, for clarity, described above and below in the context of separateembodiments, may also be provided in combination in a single embodiment.Conversely, various features of the invention that are, for brevity,described in the context of a single embodiment, may also be providedseparately or in any subcombination. Further, reference to values statedin ranges include each and every value within that range.

1. An electronic device including a radiation-emitting component or aradiation-responsive component, or a combination thereof, the electronicdevice comprising: a substrate; a first structure overlying thesubstrate, wherein the first structure is an electrically activestructure; a second structure overlying at least portions of the firststructure and the substrate, wherein: the second structure comprises afirst layer; the first layer has a first refractive index; and the firstlayer comprises a first edge; and a second layer overlying at leastportions of the first structure and the second structure, wherein: thesecond layer has a second refractive index that is lower than the firstrefractive index; the second layer includes a first portion and a secondportion; the first portion of the second layer overlies both the firststructure at the first edge and the second structure; and the secondportion of the second layer overlies the first structure but not thesecond structure.
 2. The electronic device of claim 1, wherein thesecond structure includes a well structure.
 3. The electronic device ofclaim 1, wherein the first structure further comprises a third layerhaving a third refractive index, wherein: a first difference is anabsolute value of the first refractive index minus the second refractiveindex; a second difference is an absolute value of the first refractiveindex minus the third refractive index; and the first difference islarger than the second difference.
 4. The electronic device of claim 3,wherein: the substrate comprises a fourth layer having a fourthrefractive index; and the fourth layer is optically coupled to the firstlayer, the second layer, and the third layer.
 5. The electronic deviceof claim 1, wherein the first structure has a second edge, wherein thefirst layer overlies the second edge.
 6. The electronic device of claim5, wherein the first edge of the second structure includes a recedingedge, wherein the receding edge overlies the second edge of the firststructure.
 7. The electronic device of claim 1, wherein the second layercomprises an organic active layer.
 8. The electronic device of claim 1,wherein the second structure does not have en upper portion that isspaced apart and overhangs a lower portion of the second structure,wherein the lower portion lies between the upper portion and thesubstrate.
 9. An electronic device comprising: a substrate; a firststructure overlying the substrate, wherein: the first structurecomprises a first layer having a first refractive index, a perimeter anda pattern lying within the perimeter; and the pattern extends at leastpartly through the first layer to define an opening with a first edge; asecond structure overlying the opening and at least portions of thefirst structure and the substrate, wherein: the second structurecomprises a second layer having a second refractive index that comprisesa second edge; and a third layer having a third refractive indexoverlying at least portions of the first structure and the secondstructure, wherein: the third layer includes a first portion and asecond portion; the first portion of the third layer overlies the firststructure and the second structure at the second edge; the secondportion of the third layer overties the first structure but not thesecond structure and wherein: a first difference is an absolute value ofthe first refractive index minus the second refractive index; a seconddifference is an absolute value of the first refractive index minus thethird refractive index; and the first difference is larger than thesecond difference.
 10. The electronic device of claim 9, wherein thesecond structure includes a well structure.
 11. The electronic device ofclaim 9, wherein the third layer overlies the first edge.
 12. Theelectronic device of claim 9, wherein the second edge of the secondstructure includes a receding edge, wherein the receding edge overliesthe first edge of the first structure.
 13. The electronic device ofclaim 9, wherein the third layer comprises an organic active layer.